This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We are using rhesus Epstein-Barr virus and rhesus cytomegalovirus as animal models to develop vaccines for human Epstein-Barr virus and cytomegalovirus. We need to titer stocks of each of these viruses that can be used to challenge the animals after vaccination, so that we can see if the vaccine is protective. The purpose of this study is determine the minimal infectious doses of these rhesus viruses to use a challenge inocula.